C-terminal lysine variants in fully human monoclonal antibodies: Investigation of test methods and possible causes
Article first published online: 4 MAR 2008
Copyright © 2008 Wiley Periodicals, Inc.
Biotechnology and Bioengineering
Volume 100, Issue 6, pages 1132–1143, 15 August 2008
How to Cite
Dick, L. W., Qiu, D., Mahon, D., Adamo, M. and Cheng, K.-C. (2008), C-terminal lysine variants in fully human monoclonal antibodies: Investigation of test methods and possible causes. Biotechnol. Bioeng., 100: 1132–1143. doi: 10.1002/bit.21855
- Issue published online: 13 JUN 2008
- Article first published online: 4 MAR 2008
- Accepted manuscript online: 4 MAR 2008 12:00AM EST
- Manuscript Accepted: 11 FEB 2008
- Manuscript Revised: 8 JAN 2008
- Manuscript Received: 26 JUN 2007
- lysine variants;
- post-translational modification
The C-terminal lysine variation is commonly observed in biopharmaceutical monoclonal antibodies. This modification can be important since it is found to be sensitive to the production process. The methods commonly used to probe this charge variation, including IEF, cIEF, ion-exchange chromatography, and LC-MS, were evaluated for their ability to effectively approximate relative percentages of lysine variants. A monoclonal antibody produced in a B cell hybridoma versus a CHO cell transfectoma was examined and it was determined that the relative amount of incorporated C-terminal lysine can vary greatly between these two production schemes. Another case study is shown whereby a different monoclonal antibody is subject to some minor process changes and the extent of lysine variation also exhibits a significant difference. During these studies the different methods for determining the extent of variation were evaluated and it was determined that LC-MS after trypsin digestion provides reproducible relative percentage information and has significant advantages over other methods. The final section of this work investigates the possible origins of this modification and evidence is shown that carboxypeptidase B or another basic carboxypeptidase causes this variation. Biotechnol. Biotechnol. Bioeng. 2008;100: 1132–1143. © 2008 Wiley Periodicals, Inc.